1. Field of the Invention
The present invention relates to an automatic opening/closing device of a vehicular opening/closing body, which has a function of jamming prevention.
2. Description of the Related Art
Some automobiles include opening/closing bodies such as a backdoor and a slide door, which are driven by a motor to open/close automatically (for example, refer to the gazette of Japanese Patent Laid-Open No. 2000-139095). In order to maintain an operation speed of such an opening/closing body at a specified target speed, an automatic opening/closing device of this type of the opening/closing body detects a rotary pulse of the motor by use of an encoder and the like, and then feedbacks thereto a cycle of the pulse detected by the encoder (hereinafter referred to as a rotary pulse cycle) to increase/decrease a duty (output) of the motor. Namely, when the opening/closing body lowers its operation speed below the target speed to elongate the rotary pulse cycle, the automatic opening/closing device increases the duty to enhance the operation speed of the opening/closing body. On the contrary, when the operation speed of the opening/closing body is raised more than the target speed to shorten the rotary pulse cycle, the automatic opening/closing device decreases the duty to lower the operation speed of the opening/closing body.
In the control as described above, when some foreign objects are jammed in the opening/closing body during a closing operation thereof, the opening/closing body lowers its operation speed below the target speed, and the rotary pulse cycle is also elongated more than a standard pulse time. Then, when the rotary pulse cycle longer than the standard pulse time reaches a preset jamming determining time, the automatic opening/closing device determines the above-described state as xe2x80x9cjamming,xe2x80x9d and halts the closing operation by the motor, or alternatively, inverts the closing operation to an opening operation, and thus prevents breakage of the opening/closing body.
In such related jamming determining control, as described above, when the rotary pulse cycle of the motor is elongated to a specified jamming determining time, the automatic opening/closing device determines the above-described state as a state where a foreign object is jammed in the opening/closing body, and halts the closing operation of the opening/closing body, or alternatively, inverts the closing operation to the opening operation. However, depending on the conditions of the vehicle, in some cases, a similar state to the jamming occurs though the foreign object is not jammed in the opening/closing body, and a jamming prevention mechanism malfunctions.
For example, with regard to a backdoor driven by the motor to open/close automatically, when the vehicle is parked halfway on a slope in an inclined state where the front of the vehicle faces upward, in the case of closing the backdoor electrically, a resistance due to self-weight of the backdoor is applied thereto more than when the vehicle is parked in a horizontal state. Therefore, the backdoor becomes harder to close as compared with the closing operation on the level ground, the rotary pulse cycle of the motor is elongated similarly to the case of jamming the foreign object, and the automatic opening/closing device mistakenly recognizes such a state as a jamming state in some cases.
The present invention was made paying attention to the related art as described above. The present invention provides an automatic opening/closing device of a vehicular opening/closing body, which is capable of preventing mistaken recognition of the above-described state as a jamming state.
A first aspect of the present invention is an automatic opening/closing device of a vehicular opening/closing body, including: a motor driven to open/close the opening/closing body, the motor halting a closing operation of the opening/closing body or inverting the closing operation to an opening operation when it is decided that the foreign object is jammed; and a controller for performing feedback control for a rotary pulse cycle of the motor to increase/decrease a duty in order to open/close the opening/closing body at a target speed and for determining, as jamming, a state where the rotary pulse cycle is not definitely decided before a jamming determining time comes, the jamming determining time being lowered much more than a standard pulse time corresponding to a target speed, wherein the duty is increased step by step until the rotary pulse cycle is definitely decided at a stage before the jamming determining time comes.
According to the first aspect, the duty is gradually increased until the rotary pulse cycle is definitely decided at the stage before the jamming determining time comes. Therefore, like slope parking, even in a xe2x80x9cpseudo jamming situation,xe2x80x9d where a certain state is mistakenly recognized, as a jamming state even though a foreign object is not actually jammed in the state, the duty is gradually increased, and thus the opening/closing body starts to move before the jamming determining time comes, and the rotary pulse cycle is definitely decided.
Accordingly, the xe2x80x9cpseudo jamming situationxe2x80x9d can be detected, and thus it is made possible to prevent a malfunction, in which the opening/closing body is halted or the operation thereof is inverted under the situation that is not the jamming state. Moreover, since the duty is gradually increased, the duty is not increased greatly once, and a load in the case of actually jamming a foreign object does not become excessive, resulting in safety.
Moreover, in a second aspect of the present invention, as timing of gradually increasing the duty, a pulse lowering determining time is provided, which is sufficiently longer than the standard pulse time and shorter than the jamming determining time, and after the pulse lowering determining time elapses, the duty is increased step by step for each specified duty increasing interval.
According to the second aspect, the timing of gradually increasing the duty is set after the elapse of the pulse lowering determining time longer than the standard pulse time, that is, the timing is delayed, and therefore, the duty can be increased securely after the standard pulse time elapses, and the increase of the duty becomes hard to be excessive for the amount of the delay.
Furthermore, in a third aspect of the present invention, when the rotary pulse cycle is definitely decided at the stage before the jamming determining time comes, the duty is not increased by the feedback control.
According to the third aspect, when the rotary pulse cycle is definitely decided at the state before the jamming determining time comes by gradually increasing the duty in the above-described aspects, that is, when the motor starts to move again with a fixed number of revolutions, if a long rotary pulse cycle in this case is to be subjected to the feedback control as it is, then, in order to recover the significant lowering of the operation speed, the motor rotates rapidly to close the opening/closing body rapidly. As a countermeasure therefor, the rotary pulse cycle is not to be subjected to the feedback control in this case, and the duty is maintained as it is, and thus the rapid rotation of the motor is prevented.